In 1876, Thomas Morton described Morton's Neuroma as an inflammation of a nerve in the ball of the foot. The inflammation is caused by entrapment of the nerve between the metatarsal heads. "Neuroma" means nerve tumor. Tumor in this case is simply a thickening of the irritated nerve, not a cancer.
Causes
The cause of nerve thickening is repeated injury. The nerve becomes trapped between the metatarsal heads when standing and walking. This most often occurs in a shoe with a tight toe region, high heel or thin hard sole. It usually occurs between the third and fourth toes. With repeated injury, the nerve becomes larger; as it becomes larger, it is more easily injured.
Symptoms
The symptoms of a Morton's neuroma are pain and numbness in a specific spot in the ball of the foot, sometimes extending into the toes. At times the pain may be absent and, at other times, severe enough to cause the person to stop and take off the shoe. The condition tends to get worse with time.
Diagnosis
The diagnosis, which may be difficult, is strictly based on the history of symptoms and the exam. There are no useful diagnostic tests. X-rays are normal.
Treatment
The first treatment of Morton's Neuroma is to change the shoes. A metatarsal pad in the shoe and an extra wide, soft shoe will often help. A supportive device (arch support or orthotic) with a built in metatarsal pad is often effective. A cortisone injection around the nerve may help. This will also help localize the problem.
Surgery
Surgery to remove neuroma can be done when necessary. It is successful about 95% of the time. Since the nerve is removed, a mild degree of numbness will occur in the two toes served by that nerve.
Persistent pain may be due to irritation at the cut end of the nerve, a "stump
neuroma." This can require more surgery for the five percent who do not get relief.
